Honeywell st699 to st9400c wiring

Calliman12 · Dec 26, 2022

Hello I have a question switching the above central programmers. I seem have a few more wires than other examples I’ve seen online.

For instance I have 3 wires in terminal 1 (brown and 2 red: one is a bridge to terminal 5 which I believe would be discarded); also have 3 wires into terminal 2 ( 2 blue and 1 black). This setup seems to have more wires than other examples. Can anybody guide me on how to switch over to the st9400c?

Thanks in advance.

Calliman12 · Dec 26, 2022

Photo of current wiring attached.

freddo · Dec 27, 2022

The st9400c installation manual has a terminal by terminal replacement guide chart for swapping a 699 to a 9400c
It's available here if you don't have it in the box for some reason.

If an existing terminal has more than 1 wire all those wires must go in the new terminal (except the links in terminals 5 and 8 as they are internal in the 9400c)

brianmoooore · Dec 27, 2022

The original wiring is all 'old' colours, including one of the blues, which is part of a red/blue/yellow cable.
There appears to have been a 'new' colour wire added at some time - a blue/brown flex, which may or may not be a bodge, so proceed with caution.
There's also no sign of any earth wires in your pic. Unless the wiring is really old, each of the cables should have one, and they must all be connected together..

freddo · Dec 27, 2022

The old unit appears to be fitted to a flushed in back box so hopefully the earths are connected to the earth terminal there.

brianmoooore · Dec 27, 2022

Hope full y.
................

Calliman12 · Dec 27, 2022

freddo said:
The st9400c installation manual has a terminal by terminal replacement guide chart for swapping a 699 to a 9400c
It's available here if you don't have it in the box for some reason.

If an existing terminal has more than 1 wire all those wires must go in the new terminal (except the links in terminals 5 and 8 as they are internal in the 9400c)

Thanks, any terminal with more than 1 wire went into new terminals. Fitted and working. Thanks.